Why cannot steel pipes specified in GB9948 be used in applications with PN >= 10 MPa?
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Steel pipes specified in GB9948 within GB150 can be used in applications requiring PN35MPa pressure, but for steel pipes with a pressure rating above 10MPa as specified in HG/T20581, GB6479 and 5310 are used instead of GB9948. What is the reason for this?
This post was last edited by wxd9017 on 2019-4-25 at 15:56; it’s just a man-made rule, with no particular reason behind it. It’s all the same as 150; what’s the use of my standards then?
Industry standards are stricter than **standards.
It is artificially stipulated that GB9948 imposes no restrictions
There are many such regulations. For example, why isn’t Q345 material included in GB3087, which specifies seamless steel tubes for low and medium pressure boilers? Table 3.4.2 of DL/T5054-2016 indicates that the maximum operating temperature for Q345 material is only 350 degrees Celsius, whereas the maximum temperature for materials 10 and 20 is 425 degrees Celsius